Social Interactions

Interspecific Competition Competition for shared or scarce resources Often food or space When this occurs, one of the competing species must: Migrate Adapt (shift feeding habits or behavior) Become extinct Evolve

Resource Partitioning Species competing for similar scarce resources evolve more specialized traits that allow them to use shared resources at different times, in different ways, or in different places Species 1 Species 2 Region of niche overlap Resource use Species 1 Species 2

B. Mutualism – two organisms live together, both benefit Examples: Anemone & clownfish Hippopotamus & bird Termite & amoeba that live in the intestines Cleaner fish and shrimp

Examples of mutualism in action -One version of symbiosis is the relationship of certain birds and hippopotami. -In this relationship, the birds are well known for preying on parasites that feed on each hippopotamus which are potentially harmful for the animal. -To that end, this hippopotamus openly invites the birds to hunt on its body, even going so far as to open its jaws to allow the birds to enter the mouth safely to hunt. -For the birds' part, this relationship not only is a ready source of food, but a safe one considering that few predators would dare strike at the bird at such close proximity to its host.-

Acacia Trees and Ants

A. Commensalism – two organisms live together one benefits one is unaffected Examples: Trees & orchids Monarch butterfly & milkweed Whale & barnacle

Example of Commensalism in Action: Shark & Remora Remora sharks are endowed with an adhesive disk on the dorsal surface of their heads.   They use this adhesive disk to “hitch a ride” on larger animals, usually whales, which tend to be sloppy eaters.   When food floats away from the whale’s mouth, the remora can unhitch itself and collect the scraps of food floating by. 

Parasitism – two organisms live together one benefits one is harmed Examples: Tapeworm & human Fleas & dogs

Parasitism in Action – Ticks and Dogs Ticks harm their hosts, such as dogs, by biting their skin, sucking their blood, and causing them to itch. The ticks, in turn, get food and a warm home.

Lamprey & Carp

Ecological Succession: communities in transition Gradual change in species composition of a given area over an extended period of time 2 types Primary secondary

Ecological Succession Primary Succession Begins after a disturbance to the ecosystem (ie glacier retreating, volcanic eruption, parking lot) Begins with bare rock and must form soil before plants can begin to grow Pioneer species (lichens and mosses) attach themselves to the bare rock and break it down to form soil

Ecological Succession Secondary Succession Occurs when area has been disturbed, but some soil remains Abandoned farms, burned or cut forests, flooded land Faster than primary succession